Reservoir unit

ABSTRACT

In order to fit a reservoir unit to be installed in a fuel tank in such a manner that the air-tightness of the fuel tank be not lost even if a large acceleration or deceleration works on the fuel tank, the reservoir unit is configured of an upper subunit, a lower subunit and an elastic member. The upper subunit is provided with a plate-shaped portion to block an opening formed in the fuel tank and guide rails and extending from that plate-shaped portion to the bottom of the fuel tank, and the two elements are integrally molded of resin. The lower subunit is provided with a resin-built reservoir, and slots to slidably accept the guide rails are integrally molded with the reservoir. When a large force works on the reservoir unit and the fuel tank, the guide rails and are destroyed before the plate-shaped portion would be, so that the destruction of the plate-shaped portion can be prevented.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a structure in which a reservoir unit is fitted within a fuel tank.

2. Description of the Related Art

A fuel tank of a motor vehicle requires a structure for gathering a small quantity of remaining fuel around the suction filter of the fuel pump so that, even if the quantity of the fuel remaining in the fuel tank has become very small, the suction filter of the fuel pump may not be exposed out of the fuel. Previously, as it was the usual practice to form the fuel tank of steel sheets, a fuel tank in which a sub-tank was formed around the suction filter of the fuel pump was manufactured by welding steel sheets formed into a sub-tank.

A resin-built fuel tank is beginning to be used in motor vehicles and the like. A resin-built fuel tank is usually manufactured by blow-molding synthetic resin material. In this case, it is difficult to form a sub-tank in a resin-built fuel tank. In view of this difficulty, an opening is formed in the top face of the resin-built fuel tank, and that opening is utilized for arranging a reservoir unit in the fuel tank.

A fuel tank is deformed dependent on variations in atmospheric temperature and in the quantity of fuel within, and accordingly the distance between its top and bottom varies. The suction filter of the fuel pump needs to be maintained in a position near the bottom of the fuel tank regardless of the deformation of the fuel tank.

To meet this need, the reservoir unit is configured of an upper subunit, a lower subunit and an elastic member. The upper subunit is provided with a plate-shaped portion to block an opening formed in the top face of the fuel tank. The lower subunit is provided with a resin-built reservoir, a fuel filter accommodated in the reservoir and a fuel pump also accommodated in the reservoir. To a plate-shaped portion of the upper subunit are fixed stainless steel shafts extending toward the bottom of the fuel tank. Slots to slidably accept the stainless steel shafts are molded integrally with the reservoir of the lower subunit. The elastic member, positioned between the upper subunit and the lower subunit, presses the lower subunit toward the bottom of the fuel tank.

With this structure, the distance between the upper subunit and the lower subunit varies following the deformation of the fuel tank and the consequent variation in the distance between its top and bottom. The suction filter of the fuel pump is maintained near the inner bottom of the fuel tank to match the deformation of the fuel tank.

In a reservoir unit according to the related art, when a large acceleration or deceleration is applied to the fuel tank, a large force works between the fuel tank and the reservoir unit. When the very large force works between the fuel tank and the reservoir unit, the very large force working on the lower subunit is passed on to the plate-shaped portion of the upper subunit because the conventional reservoir unit uses stainless steel shafts. For this reason, if a very large force works between the fuel tank and the reservoir unit, the plate-shaped portion of the upper subunit may be destroyed. The plate-shaped portion is particularly vulnerable to destruction where it is close to the fixed portions of the stainless steel shafts.

If the plate-shaped portion of the upper subunit of the reservoir unit is destroyed, the air-tightness of the fuel tank will be lost. Therefore, a technique to prevent the plate-shaped portion of the upper subunit from destruction even if too large a force works for the reservoir unit to escape destruction is required. Further is needed a technique to enable the motor vehicle to run as required for ensuring safety even if the reservoir unit is destroyed.

SUMMARY OF THE INVENTION

An object of the present invention, which is a technique to meet the aforementioned needs, is to realize a technique enabling the plate-shaped portion of the upper subunit to escape destruction even if otherwise too large a force works for the reservoir unit to escape destruction works.

In order to achieve this object, the invention makes use of the phenomenon that the plate-shaped portion can be prevented from destruction if the guiding part linking the upper subunit and the lower subunit is destroyed before the plate-shaped portion blocking the opening of the fuel tank is destroyed.

According to the invention, there is provided a reservoir unit to be installed in a fuel tank to be able to prevent the plate-shaped portion to block the opening of the fuel tank from destruction. This reservoir unit has an upper subunit, a lower subunit and an elastic member. The upper subunit is provided with a plate-shaped portion to block an opening formed in the top face of the fuel tank and guide rails extending from that plate-shaped portion toward the bottom of the fuel tank, the two elements being integrally molded of resin. The lower subunit is provided with a resin-built reservoir, a fuel filter accommodated in the reservoir, and a fuel pump accommodated in the reservoir, slots to slidably accept said guide rails being integrally formed in the reservoir. The elastic member, provided between the upper subunit and the lower subunit, presses the lower subunit toward the bottom of the fuel tank.

When a large force works between this reservoir unit and the fuel tank, the force working on the lower subunit concentrates on the guide rails. The guide rails and the plate-shaped portion are integrally molded of resin. The guide rails, because of their shape of extending toward the bottom of the fuel tank, are more susceptible to destruction than the plate-shaped portion blocking the opening of the fuel tank. Integral molding of the plate-shaped portion and the guide rails of resin causes the guide rails to be destroyed before the plate-shaped portion would be, and thereby, it can prevent the plate-shaped portion from being destroyed.

Further, even if the plate-shaped portion is broken, each of the upper and lower subunits can escape from destruction to keep the motor vehicle running as required for ensuring safety.

It is preferable to form said guide rails in a flat plate shape, and to bore a large hole in a part of each guide rail near the point of connection to the plate-shaped portion and to form a frail portion thin on both sides of the large hole.

In this case, as the frail portion is destroyed without fail before the plate-shaped portion would be, the destruction of plate-shaped portion can be securely prevented. Moreover, as the position of possible destruction is fixed, repair and reproduction would be easy. Furthermore, since the guide rails are formed in a flat plate shape, the section shape of the slots to be formed in the reservoir can be rectangular, so that the proportion of the volume of slots to the reservoir can be minimized.

It is preferable to form tapered projections in said slots and to bore long holes in said guide rails along the center line in the lengthwise direction, so that while the projections can be inserted into the long holes by the elastic deformation of the guide rails the return of the guide rails to their natural shape causes the projections to be engaged with end faces of the guide rails to forbid the guide rails from coming off the slots.

This configuration dispenses with any other member to prevent separation of the upper unit and the lower unit from each other, and the guide rails and the slots by themselves can prevent the upper subunit and the lower subunit from severing from each other while linking the subunits slidably.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side view of a whole reservoir unit according to the present invention.

FIG. 2A is a plan view of a reservoir according to a first preferred embodiment of the invention, and FIG. 2B is a sectional view taken along a center line (line IIB—IIB) of a jet pump in FIG. 2A.

FIGS. 3A through 3C are front views of one example and its modified versions of a partition wall according to the first embodiment of the invention.

FIG. 4A is a sectional view of a primary filter, and FIG. 4B is a plan view of the same.

FIG. 5A is a front view of an upper subunit, and FIG. 5B is a side view of the same.

FIG. 6 is a perspective view showing how guide rails and a sheath-shaped slot engage with each other.

FIG. 7 is a plan view of a reservoir according to a second preferred embodiment of the invention.

FIG. 8 is a plan view of a reservoir according to a third preferred embodiment of the invention.

FIG. 9 is a plan view of a reservoir according to a fourth preferred embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following paragraphs enumerate principal features of the preferred embodiments of the present invention to be described below.

(Mode 1) Each of the guide rails extending from the upper subunit toward the lower subunit is formed in a flat plate shape, and in the guide rail a long hole is formed extending along the center line in the lengthwise direction and at an end of this long hole toward the plate-shaped portion is formed a large hole to make both sides of it thinner so as to form a frail portion.

(Mode 2) Each of the guide rails, which are formed in a flat plate shape, has at its tip slits extending upward.

(Mode 3) Metal plates are arranged inside the slots of the reservoir.

(Mode 4) Snap fits protruding upward are integrally formed with the inner bottom of the reservoir, and engaging holes are bored on the circumference of the primary fuel filter to engage with the snap fits.

(Mode 5) The reservoir is molded of resin, and a jet pump body fitting part and a wall against which the discharge flow from the jet pump hits are integrally formed in that molded body.

(Mode 6) The reservoir is pressed toward the bottom of the fuel tank, and the opening of the jet pump toward outside the reservoir opens into a minute gap between the bottom of the reservoir and that of the fuel tank.

(Mode 7) The reservoir is substantially cylindrical, and its inner space accommodates the fuel pump and the pressure regulator.

(Mode 8) The jet pump, fuel pump and pressure regulator are assembled with the reservoir. In other words, the jet pump, fuel filter, fuel pump and pressure regulator are all put together in an assembly with the reservoir in advance.

Embodiments

A reservoir unit according to a first preferred embodiment of the present invention will now be described in detail with reference to FIG. 1.

As shown in FIG. 1, a reservoir unit 2 of the embodiment comprises an upper subunit 4 and a lower subunit 8, and installed in a fuel tank 6 when it is used. The lower subunit 8 is provided with a reservoir 20 in a cylindrical shape having a bottom (i.e. shaped substantially like a glass), a primary filter 26, a fuel pump 34, a pressure regulator 14 and a secondary filter 16. The primary filter 26, the fuel pump 34, the pressure regulator 14 and the secondary filter 16 are accommodated in the reservoir 20 to be positioned, and constitute an assembly.

The primary filter 26 , fuel pump 34, pressure regulator 14, secondary filter 16, reservoir 20 and upper subunit 4 will be described in detail below in this sequence.

The primary filter 26 is configured of a bag filter of fine-texture nylon and a resin-built frame inserted into and securing a certain volume within the bag. The inner space of the bag filter is continuous to the suction port of the fuel pump 34. The primary filter 26 is accommodated in the reservoir 20 and arranged along the inner bottom of the reservoir 20. As shown in FIGS. 4A and 4B, the frame is composed of a swelled portion 30 pressing a few parts of the bottom of the bag filter against the inner bottom of the reservoir 20, and a frame body 29 keeping the other parts of the bottom of the bag filter in a position slightly away from the bottom of the reservoir 20. This arrangement serves to secure spacing between the primary filter 26 and the inner bottom of the reservoir 20 to enable the whole filtering face to perform the filtering function.

On the circumference of the primary filter 26 are bored engaging holes 26 a to fit snap fits 31 protruding upward from the inner bottom of the reservoir 20. Engagement of the engaging holes 26 a with the snap fits 31 prevents the primary filter 26 from floating away from the inner bottom of the reservoir 20, thereby helping to keep it in a position along the inner bottom of the reservoir 20.

The meshes of the bag filter of fine-texture nylon, when exposed from the fuel, are clogged by the fuel as it surface tension works. As long as even a small part of the bag filter is soaked in the fuel, the fuel enters into the filter through the soaked part of the bag, and accordingly the bag filter can still absorb the fuel even if the remaining quantity of the fuel is so small that the top of the bag filter is exposed. Any foreign matter in the fuel is substantially removed by the primary filter 26, and the remainder is further removed by the secondary filter 16 to be elaborated upon afterwards. The fuel cleared of foreign matter by the primary filter 26 is sucked by the fuel pump.

As shown in FIG. 1, the fuel pump 34 is formed in a substantially vertical columnar shape, and has at its bottom a fuel suction pipe (not shown). To the fuel suction pipe (not shown) is connected the primary filter 26. At the top end of the fuel pump 34, there are provided an electrical connector 11 and a fuel discharge pipe 12.

The fuel pump 34, driven by being supplied with electricity through the electrical connector 11, sucks fuel in the reservoir 20 to be described afterwards from the primary filter 26, raises its pressure, and discharges it from the fuel discharge pipe 12.

To the fuel discharge pipe 12 is connected the pressure regulator 14. The pressure regulator 14 is a relief valve which, when the pressure in the fuel discharge pipe 12 surpasses a prescribed level, lets the fuel escape from the fuel discharge pipe 12 to keep the pressure within the fuel discharge pipe 12 at the prescribed level. It maintains the pressure of the fuel to be fed to the secondary filter 16, and eventually that of the fuel fed to the internal combustion engine, at the prescribed level. The fuel having escaped from the pressure regulator 14 is guided by piping (not shown in FIG. 1) into a jet pump 40 to be described afterwards. The pressure regulator 14 is accommodated in the pressure regulator fitting part 19 of a filter cover 35 to be elaborated upon afterwards, and is supported in a state of being prevented from coming off by the assembling of its cap 13 into the pressure regulator fitting part 19 of the filter cover 35.

Around the fuel pump 34 is formed a doughnut-shaped vessel 18, in which the secondary filter 16, also doughnut-shaped, is accommodated and covered by the filter cover 35 which blocks the top opening of the doughnut-shaped vessel 18. The doughnut-shaped vessel 18 and the filter cover 35 are molded resin items. The doughnut-shaped vessel 18 is bisected by the doughnut-shaped secondary filter 16 into an inner chamber and an outer chamber, and the fuel discharge pipe 12 leads to the outer chamber of the doughnut-shaped vessel 18. To the inner chamber of the doughnut-shaped vessel 18 leads a fuel feed pipe 36. The fuel delivered from the fuel pump 34 passes the secondary filter 16 from the outer chamber of the doughnut-shaped vessel 18 to reach the inner chamber of the doughnut-shaped vessel 18 and enters the fuel feed pipe 36. The fuel feed pipe 36 penetrates the upper subunit 4 and extends out of the fuel tank 6. In this embodiment according to the invention, the fuel feed pipe 36 is connected to an injector via a delivery pipe (neither shown), and supplies the injector with fuel which is raised in pressure by the fuel pump 34, regulated by the pressure regulator 14 to a constant pressure level, and cleared of foreign matter by the primary filter 26 and the secondary filter 16. Into the hollow space within the doughnut-shaped vessel 18 is inserted the fuel pump 34 from its bottom opening. Assembling of a fitting stay 25 to the bottom of the doughnut-shaped vessel 18 results in supporting of the fuel pump 34 in a state in which the pump is prevented from coming off. A cushion rubber 27 intervenes between the fuel pump 34 and the fitting stay 25 to elastically support the fuel pump 34.

Next will be described the upper subunit 4 with reference to FIG. 1 and FIGS. 5A and 5B. The upper subunit 4, which is a molded resin item, is provided with a substantially round disk portion 4 b fixed to the top face 6 a of the fuel tank 6 to block the opening of the fuel tank 6, a cylindrical wall 4 a protruding from the bottom face of the disk portion 4 b, and a pair of guide rails 10 a and 10 b extending downwards from the cylindrical wall 4 a. The cylindrical wall 4 a can be fit into the fitting holes 6 c of the fuel tank 6. As shown in FIG. 1, fitting of the upper subunit 4 to block the fitting holes 6 c of the fuel tank 6 results in arrangement and positioning of the reservoir unit 2 in the fuel tank 6. The outer circumference of the upper subunit 4 is mounted over the edges of the fitting holes 6 c of the fuel tank 6 via a seal gasket (not shown), and fastened over the fitting holes 6 c of the fuel tank 6 with bolts (not shown). This results in fixing of the upper subunit 4 to the fuel tank 6.

The upper subunit 4 has an electrical connector 9 provided with terminals vertically penetrating the disk portion 4 b. To the electrical connector 9 of the upper subunit 4 is electrically connected an electrical connector 11 of the fuel pump 34 on the lower side of the upper subunit 4. The electrical connector 9 of the upper subunit 4 is also electrically connected on the top side of the upper subunit 4 to a connector for power feed (not shown).

As well illustrated in FIGS. 5A and 5B, the pair of guide rails 10 a and 10 b extend from the cylindrical wall 4 a of the upper subunit 4. Each of the guide rails 10 a and 10 b is formed in a flat plate shape. A long hole 108 is formed along the center line of each of the guide rails 10 a and 10 b. At the top end of the long hole 108 is formed a large hole 102, and the two sides of the large hole 102 constitute a frail portion 104. At the tip of each of the guide rails 10 a and 10 b are formed slits 106 extending upwards from the lower end. The slits 106 are formed on both sides of the long hole 108.

As well illustrated in FIG. 6, the reservoir 20 has sheath-shaped slots 20 a and 20 b to accept the pair of guide rails 10 a and 10 b, and moves toward or away from the upper subunit 4 along the pair of guide rails 10 a and 10 b. Within the sheath-shaped slots 20 a and 20 b are provided tapered projections 21 a and 21 b on which the guide rails 10 a and 10 b are slidable in only one direction. When the upper subunit 4 and the lower subunit 8 are assembled, the guide rails 10 a and 10 b are elastically deformed to ride over the tapered projections 21 a and 21 b. During normal use, the tapered projections 21 a and 21 b are engaged with the ends of the long holes 108 of the guide rails 10 a and 10 b so that the upper subunit 4 and the lower subunit 8 may not sever from each other.

Inside the sheath-shaped slots 20 a and 20 b to accept the guide rails 10 a and 10 b are arranged metal plates 202. They can prevent, when the guide rails 10 a and 10 b and the slots 20 a and 20 b on the reservoir side to accept them slide relative to each other, squeaking noise or the like from arising. There is no particular limitation to the material of the metal plates 202, but stainless steel, which is resistant to corrosion, has been selected for this embodiment of the invention.

Between the upper subunit 4 and the lower subunit 8 is provided a compression spring 7 (not shown in FIG. 1) as the elastic member, and the spring 7 presses the lower subunit 8 toward the bottom 6 b of the fuel tank 6. The fuel tank 6 is blow-molded of resin, and is subject to deformation by a change in the quantity of remaining fuel and/or a change in atmospheric temperature. Therefore, the lower subunit 8 is pressed all the time toward the bottom 6 b of the fuel tank 6 correspondingly to the deformation of the fuel tank 6.

When a vehement acceleration works on the fuel tank 6, the reservoir unit 2 tends to be displaced relative to the fuel tank 6. If the guide rails 10 a and 10 b are firm then, the disk portion 4 b of the upper subunit 4 may be destroyed when the reservoir unit 2 is displaced relative to the fuel tank 6. The disk portion 4 b of the upper subunit 4 is especially subject to destruction at the roots of the guide rails 10 a and 10 b. When the disk portion 4 b is destroyed, the fuel may escape from the fuel tank 6. In the embodiment, as the frail portion 104 is formed in the guide rails 10 a and 10 b, even if a vehement acceleration works on the fuel tank 6 and the reservoir unit 2 is displaced relative to the fuel tank 6, the frail portion 104 will be destroyed first, and therefore the disk portion 4 b will not be. As there is the frail portion 104, it can prevent the disk portion 4 b from being damaged, so as to leak the fuel. To add, even if the frail portion 104 is destroyed, the fuel pump can continue to work because electric cables to drive the fuel pump and the hose to feed fuel remain connected. Thus it is possible to continue to feed fuel to the engine, and thereby enabling the motor vehicle to run as required for ensuring safety.

FIG. 2A shows a plan view of the reservoir 20, wherein the positions of the snap fits 31 are altered from those shown in FIGS. 4A and 4B. Two snap fits 31 are sufficient to keep the primary filter 26 arranged along the bottom of the reservoir 20.

FIG. 2B shows a sectional view of the jet pump 40 taken along the center line (a line IIB-IIB) shown in FIG. 2A. In the bottom of the reservoir 20, which is composed of a molded item of resin, is formed a concave 42 to accept a jet pump body 41 of the jet pump 40, and openings 44 and 46 communicating to the concave are formed, penetrating the wall of the reservoir 20. The opening 44 is fitted with a hose to connect the pressure regulator 14 and the opening 44, so that returning fuel from the pressure regulator 14 can be guided to the opening 44. The opening 46 opens into the gap between the bottom of the reservoir 20 and the bottom 6 b of the fuel tank 6. As shown in FIG. 1, a slight spacing is secured between the bottom of the reservoir 20 and the bottom 6 b of the fuel tank 6 by projections 28.

The jet pump body 41 is accommodated in the concave 42, and the subsequent fixing of a plug 38 to the reservoir 20 causes the jet pump body 41 to be fixed to the reservoir 20. The jet pump body 41 is provided with an opening 48 to accept returning fuel from the pressure regulator 14, a passage 50 for accepting fuel from outside the reservoir 20, and a venturi tube 52. When the jet pump body 41 is fixed to the reservoir 20, the opening 44 becomes continuous to the opening 48, and the opening 46, to the passage 50.

As returning fuel from the pressure regulator 14 is guided to the opening 44, that fuel passes through the venturi tube 52 of the jet pump 40 as indicated by arrow A. As the flow rate of returning fuel jetting out of the venturi tube 52 is fast, a negative pressure is generated in the downstream part of the venturi tube 52. This negative pressure causes, as indicated by arrow B, fuel outside the reservoir 20 to pass through the opening 46 and the passage 50 to be sucked by the jet pump 40 and discharged out of its discharge port 54.

From the discharge port 54 of the jet pump 40 are discharged returning fuel from the pressure regulator 14 and fuel sucked from outside the reservoir 20. Utilizing the flow velocity of returning fuel from the pressure regulator 14, the jet pump 40 introduces fuel outside the reservoir 20 into the reservoir 20.

The fuel discharged from the discharge port 54 of the jet pump 40 contains many bubbles. When it is powerfully discharged into the reservoir 20, the inner space of the reservoir may be filled with fuel containing many bubbles. If the reservoir 20 is filled with fuel containing bubbles, the fuel pump 34 may take in many bubbles and become vapor-locked, or the fuel containing bubbles may be supplied to the injector to disable the injector to inject the intended quantity of fuel.

In this embodiment according to the invention, in order to prevent the reservoir 20 from being filled with fuel containing bubbles, a wall 24 fully surrounding the discharge port 54 of the jet pump 40 is molded integrally with the resin-built reservoir 20. Thus, the flow delivered from the jet pump 40 is discharged into the closed space surrounded by the full-circle wall 24, the fuel in that closed space is cleared of the bubbles, and the fuel is moved outside the wall 24 after it is cleared of the bubbles, thereby preventing the presence of many bubbles in the fuel within the reservoir 20 outside the wall 24.

As shown in FIG. 2A, the wall 24 fully surrounds the discharge port 54 of the jet pump 40. Its height is less than that of the side wall of the reservoir 20. There is no particular limitation to the shape of the wall 24, but it preferably should have no corner in its planar view, i.e., be substantially oval or substantially circular, shaped like a bean, because any corner might invite concentration of bubbles in the fuel in that corner.

A partition wall 22 is formed at a central part in the full-circle wall 24, so configured that fuel delivered from the jet pump 40 flow round the partition wall 22. The fuel delivered from the jet pump 40 is discharged along the partition wall 22.

Clearances 56 and 58 are secured between the two sides of the partition wall 22 and the full-circle wall 24. The clearance 56 can be formed by notching a part of the wall 22 as shown in FIG. 3A. It is sufficient for the clearance 56 to permit the delivered flow to turn round the partition wall 22 a plurality of times, any of the hole-shaped clearance 56 b shown in FIG. 3B, a meshed clearance 56 c in shown in FIG. 3C or the like may be applied as appropriate.

In this embodiment according to the invention, bubbles are removed in the following manner.

(1) The fuel containing bubbles delivered from the discharge port 54 of the jet pump 40 is not directly discharged into the reservoir 20, but it goes into and fill the reservoir 20 only after it hits the wall 24 and is thereby slowed in flow rate. For this reason, the flow rate of the fuel in the reservoir 20 is slow, and bubbles contained in the fuel float so as to prevent many of them from being sucked by the fuel pump 34.

(2) When the fuel from the discharge port 54 of the jet pump 40 hits the wall 24, the removal of bubbles is accelerated.

(3) The fuel from the discharge port 54 of the jet pump 40 flows guided by the partition wall 22 and, when it sharply changes its direction in something like a U-turn at the end of the wall, the removal of bubbles is accelerated.

(4) As the fuel from the discharge port 54 of the jet pump 40 flows guided by the partition wall 22 and while it turns round the partition wall 22 a plurality of times, the removal of bubbles is accelerated.

The configuration of the walls 22 and 24 shown in FIG. 2A provides all the four of the above-described effects, resulting in virtually complete removal of bubbles.

When the quantity of bubbles contained in the fuel delivered from the jet pump 40 is small, the above-described anti-bubble measures need not be fully implemented.

In that case, for instance, the clearance 56 of the partition wall 22 on the jet pump side can be dispensed with as in the second preferred embodiment according to the invention, shown in FIG. 7.

Or, the partition wall 22 itself may be unnecessary as in the third preferred embodiment according to the invention, shown in FIG. 8.

Further, the wall which the injected flow hits against need not fully encircle the discharge port, but may only serve the purpose of letting the flow hit against as in the fourth preferred embodiment according to the invention, shown in FIG. 9. In this case, it is preferable for this wall 24 to be concavely shaped relative to the delivered flow in its planar view, because this shape would contribute to increasing the ratio of bubbles being caught.

Incidentally, although the fuel tank in the above embodiments is made of resin, the tank may be made of the conventional material, as steel plates.

While the invention has been described with reference to preferred embodiments thereof, they are presented as mere examples, but nothing to limit the scope of claims for the patent. Various modifications and alterations of the specific embodiments described above can be included within the spirit and scope of the following claims.

Further, the technical elements described in this specification or illustrated in the accompanying drawings can prove technically useful either by themselves or in various combinations, but not limited to the combinations in the claims contained in the application. The aspects of the art described in this specification or illustrated in the accompanying drawings achieve a plurality of objects at the same time, and achieving any one of those objects can be technically useful in itself.

According to the present invention, since the guide rails extending from the upper subunit to the lower subunit are integrally molded of resin with the upper subunit and the slots to accept the guide rails are formed integrally with the molding of the reservoir, when a large force is applied between the reservoir unit and the fuel tank, the force working on the lower subunit concentrates on the guide rails with the result that the guide rails are destroyed before the plate-shaped portion of the upper subunit would be. For this reason, the plate-shaped portion is not destroyed, and the air-tightness of the fuel tank is not lost.

In the invention, when the guide rails are formed in a flat plate shape and a large hole is bored in a part of each to form a frail portion thin on both sides, the frail portion will be destroyed without fail before the plate-shaped portion would be. As a result, the destruction of the plate-shaped portion can be securely prevented.

Further in the configuration described above, if tapered projections are formed in the slots and long holes to engage with the projections are bored in the guide rails, the guide rails and the slots by themselves can forbid the upper subunit and the lower subunit from severing from each other while linking the subunits slidably. 

1. A reservoir unit to be installed in a fuel tank having an upper subunit, a lower subunit and an elastic member, wherein: the upper subunit is provided with a plate-shaped portion to block an opening formed in the top face of the fuel tank and guide rails extending from that plate shaped-portion toward the bottom of the fuel tank, said plate-shaped portion and guide rails being integrally molded of resin, the lower subunit is provided with a resin-built reservoir, a fuel filter accomodated in the reservoir, and a fuel pump accommodated in the reservoir, slots to slidably accept said guide rails being integrally formed in the reservoir, the elastic member, provided between the upper subunit and the lower subunit, presses the lower subunit toward the bottom of the fuel tank, and said guide rails are formed in a flat plate shape and a large hole is bored in a part of each of said guide rails near a point of connection to the plate-shaped portion to form a frail portion thin on both sides.
 2. A reservoir unit to be installed in a fuel tank having an upper subunit, a lower subunit and an elastic member, wherein: the upper subunit is provided with a plate-shaped portion to block an opening formed in the top face of the fuel tank and guide rails extending from that plate-shaped portion toward the bottom of the fuel tank, said plate-shaped portion and guide rails being integrally molded of resin, the lower subunit is provided with a resin-built reservoir, a fuel filter accommodated in the reservoir, and a fuel pump accommodated in the reservoir, slots to slidably accept said guide rails being integrally formed in the reservoir, the elastic member, provided between the upper subunit and the lower subunit, presses the lower subunit toward the bottom of the fuel tank, and tapered stubs are formed in said slots and long holes are bored in said guide rails along the center line, and while the stubs can be inserted into the long holes by the elastic deformation of the guide rails the return of the guide rails to their natural shape causes the stubs to be engaged with end faces of the guide rails to forbid the guide rails from coming off the slots.
 3. A reservoir unit as claimed in claim 1, wherein tapered stubs are formed in said slots and long holes are bored in said guide rails along the center line, and while the stubs can be inserted into the long holes by the elastic deformation of the guide rails the return of the guide rails to their natural shape causes the stubs to be engaged with end faces of the guide rails to forbid the guide rails from coming off the slots.
 4. A reservoir unit as claimed in claim 1, wherein said fuel tank is made of resin.
 5. A reservoir unit as claimed in claim 2, wherein said fuel tank is made of resin.
 6. A reservoir unit as claimed in claim 3, wherein said fuel tank is made of resin. 